Right, but "not uncommon" is kind of evasive wording, if that's the official stance on the problem. Kind of like "It has been known to occur…" But Shiba breeders, by and large, aren't registering thyroid information with OFA, unless there's some mistake with the chart of statistics sorted by breed. MSU does have numbers which suggest that it's not common with Shibas, which I think makes it a low priority for Shiba breeders. But just from what I'm gathering anecdotally, it's definitely something worth looking into, especially for shibas with allergies, which a LOT of them are plagued with.
I'm not a member of any breed clubs, so I can't say with authority if the stance on thyroids is changing. I think it's generally of low concern, at the moment, compared to hip dysplasia, patellar luxation, eyes -- which good breeders ARE testing for.